The present invention claims priority to French Application No. 00-03074, filed on Mar. 10, 2000 which is hereby incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates generally to a ball cage and a bearing for the ball cage.
2. Discussion of the Background
Publication FR 2 665 231 describes a two-part cage, where each part includes a front face equipped with open cells, and a rear face. The cells hold a row of balls and the rear face includes means for angularly offsetting one part in relation to the other in order to reduce the distance between centers of the balls. This type of cage offers the advantage of reduced weight and bulk.
However, in practice, this type of cage with open cells must have sufficient rigidity to allow automatic fitting of the balls into the cells without causing excessive deformation of the cage body. Moreover, in order to ensure that the balls are held while fitting the cage with the balls into the bearing, it is necessary to provide proper rigidity of the cage and the cells. Proper rigidity of the cage and the cells is also necessary when the bearing is operating under stress. The rigidity of the cage and the cells is directly linked to the thickness of the cage body and the cell separation teeth. A further competing factor in constructing the bearing is the fact that the number of balls per row for a given bulk directly affects bearing performances, especially the bearing""s ability to bear heavy loads (generally speaking the larger the number of balls per row in the bearing, the greater heavy load bearing ability of the bearing). However, the bearing is generally constructed to fit within a limited area, and therefore by increasing the number of balls per row, the thickness of the cage body and cell separation teeth must be decreased.
Therefore, the inventors have determined that what is needed is a ball cage that minimizes the thickness of the cage body and teeth, yet provides the necessary rigidity to properly accommodate the balls.
Accordingly, the present invention advantageously provides a cage whose shapes are optimized to receive a maximum number of balls while retaining sufficient rigidity to ensure that the balls are held during the fitting or operating phases under bearing stress, and which is simple, lightweight and easy to manufacture.
To this end, the invention relates to a ball cage having a front face with cells for holding a row of balls and a rear face including a ring-shaped body with slots ensuring proper positioning in relation to another cage of the same type, which is interlocked to the cage. The slots each have a bottom extending in the direction of the front face as cell separation teeth. The teeth have sides that possess semispherical bearing surfaces oriented towards a center of an adjacent cell.
According to the invention, the cage preferably has a front face that includes a closing ring linking the peripheral extremities of the teeth.
According to a preferred characteristic of the invention, the teeth are locally of highly reduced thickness at the radial height of the center of the balls.
According to another preferred characteristic of the invention, the teeth extend obliquely from the ring-shaped body of the rear face and are at a radial height which is lower than the radial height of the center of the balls, up to the ring of the front face, which is at a radial height which is higher than the radial height of the center of the balls.
According to another preferred characteristic of the invention, the teeth extend approximately 45xc2x0 in relation to a cage axis.
According to another preferred characteristic of the invention, the ring includes, at a periphery of the balls, an inner face equipped with semispherical bearing surfaces oriented toward the center of the adjacent cells.
According to another preferred characteristic of the invention, the ring is axially recessed in relation to the axial extremity of the balls.
According to another preferred characteristic of the invention, the ring includes an inner radial edge which presents a circular cutout opposite each ball. The cutout corresponds to the intersection of the semispherical bearing surface of the cells with the plane of the front face, and allows the balls to overflow or extend beyond the front face.
According to another preferred characteristic of the invention, the inner edge of the ring-shaped body of the rear face includes holding clips.
The present invention also advantageously concerns a bearing for a row of balls, which includes a cage with the characteristics described above.
The invention also advantageously concerns a bearing for two rows of balls, which includes two cages with the characteristics described above, where the slots of the cages are interlocking.